Jump starting M-- Help

The 1939 M LP has been setting for about 2 yrs. Has no battery. I tried to jump start it with the SM (12 volt with alt.) hooked to top of starter switch and neg. cable to starter bolt.Both cables where hooked to SM battery first. When pushing starter switch in, fire shot out from ground connection.Motor did not turn. Checked ampmeter on SM and not charging. Alt . blown. Never heard of this befor. Need help. Buck

How do I say OH SH*T? First, all you did was create a dead short when you hooked it up that way and hit the switch. IF you didn't burn everything out and ruin the alternator on the other, then let's try this step by step.
1. I am presuming that this is a 6 volt positive ground system. If it is a negative ground system, then revers the jumper leads.
2. Hook up the positive lead to the frame of the tractor. Remember to make sure that it is a clean unpainted area as close to the started as you can. I usually look for a mounting bolt on the starter.
3. MAKE SURE THE TRANSMISSION IS IN NEUTRAL!!!!!!
4. Set brake
5. Make sure the lights and all accessories are off, and I recommend unhooking the tractor battery if its dead. ( saw a dead 6 volt blow up one day when someone tried jumping it with a 12 volt system.) Just a precaution I would take. You do as you like.
6. Now hook up the negative lead of the cable to the battery side of the starter solenoid.
7. Turn on the ignition and attempt your start.
CAUTION: Do not engage the starter for more than 15-30 seconds in a 5 minute time frame as you will burn it and your starter solenoid. It is designed for 6 volts and I have used 6 volt starters on 12 volt systems for years but they will spin faster and will get hotter faster. Whats real common is to get it hot enough that the solder melts on the armature and the centrifugal force throws the solder out and then the wires come off the commutator and the armature ends up looking like a wire brush at the end.
NOTE2: I am also presuming that you have a magneto ignition system.
Good luck, LarryT

Always, always, ALWAYS connect POS to POS, and NEG to NEG when jump-starting ANYTHING.

When in doubt, pull the battery out. If you connect directly to the battery, and follow one simple rule, it doesn't matter what type of ground the tractor has.

...but yes, just like Larry says, you created a dead short and fried your alternator.

This is because you connected the NEG on the SM to the POS on the M. As soon as you pulled that switch, you created a short circuit between the two batteries.

OUCH

First of all was the jump tractor SM Neg ground which is my guess if it has an alternator???

REGARDLESS ALWAYS jump or charge Pos to Pos and Neg to Neg as posted below. Hope your alternator didnt get damaged????

Next, if youre trying to jump start a tractor LPM with no battery at all, tHE jumper battery SM basically replaces the LPM battery and you could attach the jumper cables to the battery cable ends OBSERVING CORRECT POLARITY

We recently covered how to jump start THE STARTER MOTOR ONLY while allowing the tractors battery to power the ignition if needed but since your LPM has no battery (and if needed if its NOT a Mag ignition) that dont work so you have to go the route of the paragraph above.

Another way to replace battery jump a tractor that has no battery (same as attaching to battery cable ends) is to attach one jumper cable to the Battery input (NOT to starter) side side of a starter switch or solenoid and the other jumper cable to case/frame/ground (observing correct polarity) That way if you turn on ignition and/or depress a start switch or solenoid key/switch activation its the same as if the dead non battery tractor has its own battery.
IF YOU HOOKED ONE JUMPER LEAD TO THE OUTPUT OF A START SWITCH OR SOLENOID AND THE OTHER TO THE STARTER POST THATS A DEAD SHORT AND VERY HAZARDOUS

If youre jumpimg a starter motor I always attach the FIRST lead to the starter post/stud or the output (to starter NOT to battery) side of a start switch or solenoid and make the LAST connection to a clean non painted part of the frame case of the tractor near the starter as its usualy easier to get a good bite to frame versus a starter stud and theres also less chance of a short if youre trying to jump to the starter post/stud when all is hot (cuz the ground was made first)

Hope this helps, post back any questions

DO NOT USE A 12 VOLT BATTERY TO JUMP RIGHT ON/TO A 6 VOLT BATTERY, THE 6 VOLT COULD POTENTIALLY BLOW UP

John T

I agree with John T.
The first thing is to see if the Running tractor is still operational.
With all jumpers disconnected, and the tractor running, turn on the lights. If the amp gauge needle flickers and then stays in the middle, it is probably OK. If it goes to discharge, it probably needs to be repaired. Check running voltage across the battery it should be about 14.2 to 14.6 volts. Battery voltage is about 12.6 or so, if this is the reading, the alt will need analysis.

The second question is if the tractor with no battery also had an alternator and is 12 volt. If it did, and it was also negative ground, (probable) you were doing things that if just to see if it would start would be OK but risky.
An alternator system needs a battery in all cases to control voltage. If you had gotten it started and disconnected the SM, it could have toasted components on the LPM.

Always assume the need for an installed battery in an electrical system.

If it was a 6v generator based LPM, (assuming the battery leads were isolated from touching ground on the LPM) and if the LPM was magneto equipped, the tactics used would have been better if the jumper was used to touch the starter input on the LPM, and not the starter switch lead. Jim

With respect, there was no second battery. Jim

Lary T., John T., and Mkirsch Gee you all gave me lots of info here. The LP M is a mag ignition and the stater switch is the old original switch operated with the foot. No solinoid.Have run LP for yrs. with no battery.I first hooked pos. 12v cable, with SM tractor runing, to starter switch connection leading to starter. Started to hooked ground from neg. cable on SM to starter bolt to motor on LP. Fire shot every where.NOT GOOD. I switched pos. cable to upper connection of stater switch, which is where battery would be connected if had one.Then I hit starter switch and fire shot from starter ground bolt connection.Looked at ampmeter on SM. No chg.. I think the first hook-up attempt knocked alt. out. If motor stuck would it cause all this fire to happen? Thanks for all your help. To me this is the way I've always started this tractor. Buck

Jim-- I just saw your comment . The LP does't have an alt. or gen. and I think when I looked at amp guage , tractor still hooked up to other tractor.Just unhooked it and put Sm back in barn. I was too unhappy about ruining the Alt. to check it out and went home. Too much cold and snow to check Sm out now . Thanks so much for your input. Will do what you and others have said when weather better. Buck Clayton

Try to turn the engine over using the fan. Sounds like it may be tight. (starter locked). Without a battery it makes no difference as to + or - ground. Just make sure the circuit is through the starter & not cable to cable. The cable that comes from the starter to the battery wasn"t touching ground was it?

Teddy52food, The starter cable could have been touching trans. case. I usally have it in safe place. No, I didn't check that.Could have had it taped up long time ago or taken off. Sounds very logical and I can see how this could cause this kind of spark. This tractor is not used much and I didn't want to buy a $70 battery. I will try turning engine when we have a good day. Thanks so much for all the good help you and the others have given an old man in need. Buck

...This tractor is not used much and I didn't want to buy a $70 battery...

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Junkyard. BTW, how did he ground out his SM? If one was hooked to the starter switch (+, other than if the cable he clamped onto was touching the frame, but it wasn't bc it would have sparked right away) and one was hooked to the starter bolt (-) how does that short out the SM???

sflem 849 I just came back on and found your comment. I have been starting this tractor for years from SM.No Trouble. Since it is a magnito ignition' motor just needs to be cranked to run.The starter was overhauled 3 yrs. ago. Don't think it would do this. If motor stuck, would it cause too much load on SM electrical system? Thanks for your reply. As I said earlier,when a warm day comes I'm sure going to check all this out. Buck Clayton

(quoted from post at 14:58:31 01/10/11) sflem 849 I just came back on and found your comment. I have been starting this tractor for years from SM.No Trouble. Since it is a magnito ignition' motor just needs to be cranked to run.The starter was overhauled 3 yrs. ago. Don't think it would do this. If motor stuck, would it cause too much load on SM electrical system? Thanks for your reply. As I said earlier,when a warm day comes I'm sure going to check all this out. Buck Clayton

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That makes sense to me, I just didn't understand how everybody figured it grounded out bc you hooked it up wrong. It seemed you hooked it up right to me.
BTW, if I have two people I always like the chain method better I start my H w a mag all the time by pulling it. No battery in there. My starter/charger is not good enough to start the tractor by itself. Never tried to jump it with another tractor.

You could just stick a cheap 12 volt battery in the Lp tractor. It only gets used for starting, so it will run it a while between having to charge it. A remote jumpstarting stud would also let you hook the cables to it without having the chance of shorting onto the switch housing or the starter rod.